Replacing rear coil springs on donor built MKIV

[JCB52]

I would like to replace the donor rear coils on my MKIV because they’re a “giant pain” to adjust. Is it reasonable easy to replace them with coil- overs and keep the quad shocks?

[cob427sc]

I don't understand "adjust the donor coil springs" as there is no adjustment in the donor rear suspension of that type. It's an easy change over to the coilovers and the quad shocks go to the junk pile. Just look up in the build manual and it will show you both suspension installs.

[Jeff Kleiner]

I don't understand "adjust the donor coil springs" as there is no adjustment in the donor rear suspension of that type.

Actually, yes there is. The donor spring threads onto FFR perches allowing them to be screwed up or down to adjust ride height.

Jeff

[Norm B]

I originally had the donor springs and made a locking mechanism out of a cable clamp to stop the spring from rotating after adjustment. Was never satisfied with the handling. Rear suspension was too soft compared with the front and the car had some quirky handling characteristics.
Upgraded to coil overs and kept the quad shocks. Had to move the quad shock frame mount aft so the shock body would clear the coil over spring.

Norm

[cob427sc]

I stand corrected! The only cobra I built with the donor suspension in the rear was my first back in 1998. Guess I forgot what it was like.

[JCB52]

I originally had the donor springs and made a locking mechanism out of a cable clamp to stop the spring from rotating after adjustment. Was never satisfied with the handling. Rear suspension was too soft compared with the front and the car had some quirky handling characteristics.
Upgraded to coil overs and kept the quad shocks. Had to move the quad shock frame mount aft so the shock body would clear the coil over spring.

Norm

This is what I want to do. Norm, could you give some more details about this modification. And, what coil overs and spring pressure you used. Thanks a bunch…

[Norm B]

The coil overs and springs are the Factory Five standard ones sold for the solid axle rear end. They have 350lb springs. With the quad shocks I have, I needed to move the frame mount back about 2 inches to clear the coil over spring. Not all quad shocks are the same so you might not need the same modifications. Don’t believe the quad shocks are required with the coil overs but, I had them already and decided to use them.
I have Granatelli control arms with poly bushings on the rear. As recommended by Jeff I kept the stock Ford rubber bushings on the differential. There’s no axle hop and handling is much better than the donor springs. The ride is much firmer though.

Norm

PS I see that FFR has the coil overs listed as out of stock. Check the classifieds on this and the other forum. That’s where I got mine.

[Jeff Kleiner]

Norm

PS I see that FFR has the coil overs listed as out of stock. Check the classifieds on this and the other forum. That’s where I got mine.

Call them. The parts catalog is frequently not current regarding availability. If you change to coilovers be sure to also change the lower axle brackets (FFR sometimes calls them Traction Lock brackets) so that the lower end of the coilover is properly installed in double shear.

Jeff